Temperature-controlled rework system

ABSTRACT

A temperature-controlled rework system comprises a manifold assembly adapted to direct a cooling gas flow toward an area of a printed circuit board adjacent a rework zone to reduce a temperature of the adjacent area to below a temperature of the rework zone. The system also comprises a temperature control system adapted to monitor the temperature of the adjacent area.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to the field of electronicequipment and, more particularly, to a temperature-controlled reworksystem.

BACKGROUND OF THE INVENTION

As the functionality and sophistication of electronic equipmentincreases, the complexity of the electronic equipment also increases.For example, electronic equipment often comprise a single- ormulti-layer printed circuit board containing a variety of electroniccomponents, such as application specific integrated circuits.Additionally, the density of the electronic components on the printedcircuit board also increases.

In the course of testing, assembly or use, electronic components on theprinted circuit board may require removal or replacement. However, thedensity of the components on the printed circuit board generally makescomponent replacement a difficult and delicate task. For example, onemethod for replacing an electronic component includes directing a streamof high temperature gas toward the component to soften or re-liquefy thesolder coupling the component to the circuit board. However, adjacentcomponents become a concern because the high temperature gas mayre-liquefy adjacent component solder-connections, thereby possiblycausing a disconnection between the adjacent component and the circuitboard. Additionally, the high temperature gas flow may detrimentallyaffect the adjacent component.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, atemperature-controlled rework system comprises a manifold assemblyadapted to direct a cooling gas flow toward an area of a printed circuitboard adjacent a rework zone to reduce a temperature of the adjacentarea to below a temperature of the rework zone. The system alsocomprises a temperature control system adapted to monitor thetemperature of the adjacent area.

In accordance with another embodiment of the present invention, a reworkmanifold assembly comprises a manifold having a plurality of aperturesadapted to direct a gas flow to an area of a printed circuit boardadjacent a rework zone. The rework manifold also comprises a pluralityof supports adapted to support the manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following descriptionstaken in connection with the accompanying drawings in which:

FIG. 1 is a diagram illustrating an embodiment of atemperature-controlled rework system in accordance with the presentinvention; and

FIG. 2 is a diagram illustrating a side view of thetemperature-controlled rework system illustrated in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present invention and the advantagesthereof are best understood by referring to FIGS. 1 and 2 of thedrawings, like numerals being used for like and corresponding parts ofthe various drawings.

FIG. 1 is a diagram illustrating an embodiment of atemperature-controlled rework system 10 in accordance with the presentinvention. Briefly, system 10 is used to enable or assist in the removalof an electronic component 12 from a printed circuit board 14 or othertype of electronic structure. For example, electronic component 12 maycomprise an integrated circuit, resistor, capacitor, or any other typeof device soldered to printed circuit board 14. In the embodimentillustrated in FIG. 1, system 10 comprises a manifold assembly 20, a gasflow system 22, a temperature control system 24, and a controller 26 tomonitor and regulate temperature levels surrounding or adjacent to arework zone 28. As used herein, “rework zone” comprises an area about aparticular component 12 to receive a relatively high temperature gasflow 30 for re-liquefying solder connecting the particular component 12to printed circuit board 14 to enable or assist in the removal of theparticular component 12.

Briefly, air flow system 22 delivers a relatively cool or lowtemperature gas flow to manifold assembly 20 for cooling or maintainingareas of printed circuit board 14 adjacent to rework zone 28 at areduced temperature to substantially prevent the re-liquification ofsolder attachments of adjacent components 12, thereby maintaining theadjacent components 12 at a reduced temperature and protecting theadjacent components 12 from elevated temperatures which may otherwisedetrimentally affect the adjacent components 12. In the embodimentillustrated in FIG. 1, manifold assembly 20 comprises a centrallydisposed opening 40 for receiving a nozzle 42 which may be used todirect a high temperature gas flow 30 into rework zone 28 to re-liquefysolder attaching a particular component 12 to printed circuit board 14.However, it should be understood that other devices or methods fordirecting the high temperature gas flow 30 into rework zone 28 may beused. Additionally, manifold assembly 20 may also be formed havingdifferent geometric characteristics to accommodate different types ofdevices which may be used to deliver the high temperature gas flow 30 torework zone 28. Thus, in operation, manifold assembly 20 receives areduced temperature gas flow via air flow system 22 and directs thereduced temperature air flow about a perimeter of rework zone 28 tomaintain components 12 in areas adjacent to rework zone 28 at a reducedtemperature.

Temperature control system 24 is used to monitor the temperature ofareas of printed circuit board 14 adjacent rework zone 28. Controller 26is coupled to temperature control system 24 and air flow system 22 toregulate the reduced temperature air flow delivered to manifold assembly20 based on temperatures of areas of printed circuit board 14 adjacentto rework zone 28. Controller 26 may comprise a computer, workstation,or other type of processing device or system. Controller 26 may be usedto regulate the temperature of the reduced temperature air flowdelivered to manifold assembly 20 and/or regulate the volume of thereduced temperature air flow delivered to manifold assembly 20. Thus, inoperation, temperature control system 24 monitors and determinestemperature conditions of areas adjacent to rework zone 28 so thatcontroller 26 may regulate the reduced temperature air flow delivered tomanifold assembly 20 via air flow system 22 to prevent adjacent areasand components 12 of printed circuit board 14 from being exposed toelevated temperatures which may otherwise detrimentally affect theadjacent components 12.

FIG. 2 is a section view taken along the line 2-2 of FIG. 1 illustratingsystem 10. As illustrated in FIG. 2, nozzle 42 may be inserted withinopening 40 of manifold assembly 20 in close proximity to a particularcomponent 12 within rework zone 28 to direct the high temperature gasflow 30 into rework zone 28 to re-liquefy solder attachments forcomponent 12 within rework zone 28. In the embodiment illustrated inFIG. 2, manifold assembly 20 comprises a manifold 50 having an internalcavity 52 for receiving the reduced temperature air flow from air flowsystem 22. Manifold 50 also comprises a plurality of apertures 54disposed in a downwardly facing wall 56 to direct the reducedtemperature gas flow, indicated generally at 58, from within cavity 52towards areas of printed circuit board 14 and components 12 disposedadjacent to rework zone 28. Apertures 54 may be disposed in any varietyof arrays or geometric patterns to provide equal or unequaldistributions of reduced temperature gas flow 58 to areas of printedcircuit board 14 adjacent rework zone 28. For example, manifold 50 maybe configured having a greater concentration of apertures 54 disposednear rework zone 28 and a lesser concentration of apertures 54 disposednear areas farthest from rework zone 28 to provide greater temperaturereduction in the areas of printed circuit board 14 immediately adjacentto rework zone 28. The sizes of apertures 54 may also be varied toprovide increased volumes of gas flow 58 to areas immediately adjacentto rework zone 28. However, it should be understood that other patterns,arrangements, sizes, and/or arrays of apertures 54 may be used onmanifold 50.

As illustrated in FIG. 2, manifold assembly 20 also comprises aplurality of supports 60 for supporting manifold 50 proximate to reworkzone 28. Preferably, supports 60 comprise flexible members toaccommodate height variations relative to printed circuit board 14caused by various sizes of components 12 or other structure so that adownward force may be applied to an upper surface 62 of manifold 50 tomaintain a desired position of manifold 50 relative to printed circuitboard 14 and/or rework zone 28. For example, in the embodimentillustrated in FIG. 2, supports 60 comprise springs 64 to accommodateheight variations in printed circuit board 14; however, it should beunderstood that other types of flexible supports 60 may be used.Additionally, it should be understood that other types of supports 60,both flexible and rigid, may be used to support manifold 50 a desireddistance relative to printed circuit board 14 and/or rework zone 28.

In the embodiment illustrated in FIG. 2, temperature control system 24comprises temperature sensors 70 for monitoring a temperature of areasof printed circuit board 14 adjacent to rework zone 28. Temperaturesensors 70 may comprise thermocouples or other types of devices formonitoring temperature conditions. As illustrated in FIG. 2, temperaturesensor 70 are disposed at varying distances from rework zone 28 toenable a temperature profile to be obtained for areas of printed circuitboard 14 adjacent to rework zone 28. In FIG. 2, temperature sensors 70extend downwardly from manifold 50 through springs 64 to a locationproximate to printed circuit board 14; however, it should be understoodthat the locations and/or positions of temperature sensors 70 may beotherwise located relative to manifold 50 and printed circuit board 14.

Thus, in operation, high temperature gas flow 30 is directed downwardlyto rework zone 28 to re-liquefy solder attaching a particular component12 disposed within rework zone 28. Meanwhile, reduced temperature gasflow 58 is delivered from air flow system 22 to manifold assembly 20where manifold 50 distributes reduced temperature gas flow 58 to areasadjacent to rework zone 28 to maintain the adjacent areas at a reducedtemperature. Based on a temperature and/or temperature profile of areasadjacent rework zone 28 as determined via temperature control system 24,controller 26 regulates the temperature and/or flow rate of the reducedtemperature gas flow 58 delivered to manifold assembly 20 via air flowsystem 22. Thus, system 10 reduces the temperature of the areas ofprinted circuit board 14 adjacent to rework zone 28 and provides amethod of maintaining adjacent areas and components 12 of printedcircuit board 14 preferably at a reduced temperature relative to reworkzone 28, thereby protecting adjacent components 12 from elevatedtemperatures which may otherwise detrimentally affect the adjacentcomponents 12.

1-21. (canceled)
 22. A rework system, comprising: a manifold assemblyadapted to deliver a low temperature gas flow to an area of a printedcircuit board adjacent a rework zone, the manifold assembly adapted tocooperate with a nozzle for directing a high temperature gas flow towardthe rework zone.
 23. The system of claim 22, wherein the manifoldassembly comprises an opening for receiving the nozzle.
 24. The systemof claim 22, wherein the manifold assembly comprises a manifold havingplurality of apertures for delivering the low temperature gas flow. 25.The system of claim 22, wherein the manifold assembly is adapted todeliver the low temperature gas flow about a perimeter of the reworkzone.
 26. The system of claim 22, wherein the manifold assemblycomprises a plurality of supports adapted to support a manifold of themanifold assembly a desired distance from the printed circuit board. 27.The system of claim 22, wherein the manifold assembly comprises aplurality of flexible supports.
 28. The system of claim 22, wherein themanifold assembly comprises a plurality of supports adapted toaccommodate height variations of the printed circuit board.
 29. Thesystem of claim 22, wherein the manifold assembly comprises a pluralityof supports adapted to support a manifold of the manifold assembly adesired distance from the printed circuit board in response to a forceapplied to the manifold toward the printed circuit board.
 30. A reworkassembly, comprising: means for delivering a low temperature gas flow toan area of a printed circuit board adjacent a rework zone; and meansformed in the delivering means for cooperating with a means fordirecting a high temperature gas flow toward the rework zone.
 31. Thesystem of claim 30, wherein the delivering means comprises means fordelivering the low temperature gas flow about a perimeter of the reworkzone.
 32. The system of claim 30, wherein the delivering means comprisesmeans for supporting a manifold of the delivering means a desireddistance from the printed circuit board.
 33. The system of claim 30,wherein the delivering means comprises means for accommodating heightvariations of the printed circuit board.
 34. The system of claim 30,wherein the delivering means comprises means for supporting a manifoldof the delivering means a desired distance from the printed circuitboard in response to a force applied to the manifold toward the printedcircuit board.
 35. A rework system, comprising: a nozzle adapted todirect a high temperature gas flow toward a rework zone of a printedcircuit board; and a manifold assembly disposed about a perimeter of thenozzle for delivering a low temperature gas flow about the perimeter ofthe rework zone.
 36. The system of claim 35, wherein the manifoldassembly comprises a centrally disposed opening for receiving thenozzle.
 37. The system of claim 35, wherein the manifold assemblycomprises a plurality of flexible supports.
 38. The system of claim 35,wherein the manifold assembly is adapted to accommodate heightvariations of the printed circuit board.
 39. The system of claim 35,wherein the manifold assembly comprises a plurality of supports forsupporting a manifold a desired distance from the printed circuit board.40. The system of claim 35, wherein the manifold assembly comprises aplurality of supports for supporting a manifold a desired distance fromthe printed circuit board in response to a force applied to the manifoldtoward the printed circuit board.